The Travato 59g has a 3 way fridge which allows the option of running the unit with 12v power from the coach battery while traveling. This works well as the alternator easily keeps up with the draw, you don't use propane and there are no worries at fuelling stops with open flames. (Full disclosure: I previously always used the fridge on propane when driving and usually never turned it off at gas stations.)
Where the 12v option fails is when you forget to turn it off or forget to switch to another heat source when you park and shut off the engine. The draw on the battery is huge and you can use up a good portion of its capacity in just a few hours. What I've set out to do is to modify the fridge control so that it will only run on 12v when the engine is also running and will shut off when the engine is shut off. This mod was suggested by a post from member “hbn7hj”
. I've never wired up a relay so I watched a bunch of videos on how they work so here goes.
This first photo is a view from underside the rear of the coach. You can see a corner of the green generator but what we're interested in is that black box behind it.
If you remove 6 screws, two on each side and two on the front side, the cover will come off and it looks like this.
That silver canister is the isolator relay. It combines the coach battery and the chassis battery so that they both receive a charge from the alternator when the engine is running, When the engine is off, the batteries are separated again. That center bolt has a wire (the one with the yellow insulator) that is connected somehow to the alternator and that wire is hot when the engine is on. I think that's how it works because it has no voltage when the key is on, only when the engine is running and then only after a delay of a couple of seconds. Anyway that terminal is where we will get the signal that will tell the fridge that the engine is on so I ran a wire, the black one that goes off to the right, from that screw into the compartment at the rear of the fridge securing it using all the clamps and wraps that were already installed by Winnebago to hold other wires.
This is a picture of the back of the refrigerator. Towards the center you will see a small black cube that is a 30 amp relay. It has four terminals. Terminal 85 is connected to the selector switch on the refrigerator, terminal 86 goes to ground. 12V positive comes in terminal 30 and when the power selector switch is turned to 12v, the relay is energized and power is applied to the 12v heater out terminal 87.
What I want to do is intercept the power that is going to the heater and make it conditional on the engine running so I bought another 30 amp relay at O'Reilly's. This one is a 5 terminal relay. You'll see why later.
Terminal 85 will receive the wire from the battery isolator relay that we ran and terminal 86 will go to ground. The wire from the heater that was attached to the factory relay at terminal 87 will go to the new relay's terminal 87 and a short wire will connect the two relays from the old terminal 87 to the new terminal 30. Now the fridge must meet two condtions before the 12v heater will operate. The selector must be turned to 12v and the engine must be running.
Here's what both relays wired up look like.
To be continued...
Never forget to turn off fridge again
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